The invention relates to the field of the manufacture and the method of operation of vehicles and vehicle components. In particular, the invention relates to land vehicles for daily road traffic, in particular motor vehicles, such as, for example, utility or commercial vehicles. The invention relates, in particular, to a control device for a compressed air system of a vehicle. The terms commercial vehicle and utility vehicle are used interchangeably herein.
Vehicles in daily road traffic frequently travel temporarily in overrun conditions depending on the instantaneous speed, acceleration of the vehicle (positive or else negative, for example in the case of braking) or other external influences such as interventions by the driver.
Overrun conditions means here the drag mode of the engine as a result of the kinetic energy of the vehicle which is fed in via the closed drivetrain. The vehicle, which at the time of the overrun conditions has more kinetic energy than the engine is making available at that moment, drags the engine, i.e. attempts to accelerate it.
On a flat road surface, what are understood to be overrun conditions are possible only if the driver brakes the vehicle by taking his foot off the gas pedal. On a negative gradient, these overrun conditions can occur for a relative long time either with a positive or negative vehicle acceleration or with a constant velocity depending on their degree and the driver's reaction at the gas pedal.
Overrun condition phases only make up a relatively small proportion of the entire travel time. In particular, hitherto it has not been possible to predict when overrun conditions will occur in a vehicle since the behavior of the driver has a significant influence on this. However, the driving behavior of the driver is not predictable, for which reason there is conventionally no possible way of predicting any possible overrun condition phases before they actually occur. The uncertainty in terms of the future or imminent driving behavior of the driver and therefore his vehicle prevents overrun condition phases which occur from being utilized technically more efficiently. Vehicle components can be controlled in a changed way only in the case of an overrun condition phase which has already commenced and is still continuing. However, conventionally there is also uncertainty here about the duration for which an overrun condition phase, which has already commenced, will still continue since, apart from the driver's reaction, the future operating states of the vehicle, which are partially conditioned by the section of road, are unknown. This limits the possibilities of optimizing control of vehicle components. Owing to the many unpredictable influences, there is not yet any way of overcoming the above-mentioned limitations with respect to the control and method of operation of vehicle components.
In particular, compressed air systems such as are necessary, for example, for a brake system can conventionally be controlled only with the above restrictions.
The object of the present invention is to utilize prior knowledge of overrun condition phases in vehicles, in particular of land vehicles such as, for example, road vehicles, to control a compressed air system, for example, for a brake system. The intention is in particular to make available a device which is suitable for this.
The present invention makes it possible for the first time to utilize the cartographic altitude positions of a section of road, i.e. its local altitude coordinates (in the perpendicular direction with respect to the surface of the earth) in a technical manner in order to predict the occurrence of overrun condition phases of a mobile vehicle and therefore to control a compressed air system, for example a brake system of a commercial vehicle. Hitherto, navigations systems in mobile vehicles were used only to provide the driver with an orientation in the two-dimensional road network and to calculate the shortest or the fastest route for the purpose of route planning. Altitude coordinates do not play a role in this since the vehicle is tied to the respective road and must necessarily follow its altitude profile; only the horizontal coordinates parallel to the surface of the earth (in the positive y/x directions and in the North/South/East/West directions) are significant for the instantaneous position of the vehicle in the road network and for the resulting shortest route (the profile of which is correspondingly also represented only two-dimensionally). Conventionally, altitude coordinates are also not utilized in a technical manner to control a component of a vehicle, but rather exclusively for finding the route to a destination.
On the other hand, the invention permits for the first time optimization of the operational sequence or the control processes of the vehicle, in particular of a component of the vehicle such as, for example, a compressed air system, in particular a brake system, as a function of parts of a section of road lying ahead of the vehicle which have negative gradients. Conventionally, only the parameters of the actual vehicle which indicate the respective operating states of the vehicle components are used as influencing variables for controlling and optimizing them but not the cartographic data of a section of road being traveled on. The invention permits vertical position coordinates of the section of road and/or of the vehicle to be included in order to calculate in advance the future driving behavior of the vehicle and, in particular, calculate a prediction about the overrun condition phases that are expected to occur. On the basis of said overrun condition phases it is possible to improve the control of one or more vehicle components. It is therefore possible, for example, to detect in advance whether and when an overrun condition phase, which continues for a relatively long time, is imminent, during which phase a control process, switching process or other working step of a vehicle component can be carried out without consuming energy or with relatively low consumption of energy. While the imminent driving behavior of the driver is conventionally considered to be unpredictable, the present invention permits a qualitative technological advance in terms of the control and method of operation of vehicle components taking into account influencing variables which lie outside the vehicle itself. Any desired vehicle components, in particular components of road-bound vehicles, for example of utility vehicles, can benefit from this.
In particular, it becomes possible to detect overrun conditions or overrun condition phases in advance and to utilize them technically in the vehicle. In particular, phases in which the vehicle engine of the traveling vehicle receives, via its connection to the vehicle wheels, an additional torque, which has the effect of increasing the engine speed, can be utilized for energy-saving or energy-free execution of a control process, switching process or other working step of any desired vehicle component.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.